What kind of sealing form does the air compressor generally use?
In centrifugal compressors, in order to reduce air leakage in the gap between the compressor rotor and the stationary element, a seal is necessary. Seals can be divided into four types according to their positions: wheel cover seals, interstage seals, balance disc seals and (front and rear) shaft seals. The form of seal is usually comb-type labyrinth seal, in addition, graphite ring seal, fixed sleeve liquid film seal, floating ring seal and mechanical seal can be used.
The working principle of the air compressor seal: When the air flow passes through the gap of the comb-shaped sealing sheet, the air flow approximately undergoes an ideal throttling process, its pressure and temperature decrease, and the speed increases. When the airflow enters the cavity between the sealing sheets from the gap, due to the sudden expansion of the cross-sectional area, the airflow forms a strong vortex, so that the speed almost disappears completely, and the temperature returns to the value before the sealing sheet, but the pressure can no longer be restored. , keep equal to the pressure when passing through the throttling gap. The air flow passes through each subsequent sealing sheet gap and cavity, and the change of air flow repeats the above process. The difference is that as the mass volume of the airflow increases gradually, the airflow velocity and pressure drop across the gap become larger and larger. It can be seen that when the airflow passes through the entire labyrinth seal, the pressure gradually decreases, and finally approaches the back pressure, thus playing a sealing role.
